Whole Exome Sequencing

What is Whole Exome Sequencing?

Whole Exome Sequencing (WES) is a technique for sequencing the exonic regions on the DNA. Exome comprises about 1-2% of the whole GENOME, CODES FOR ~23,000 GENES IN HUMANS. Being the protein coding region, ~85% OF disease-causing mutations in Mendelian disorders and many disease-predisposing SNPs are clinically associated with the exomes, sequencing the entire exome can provide detailed insights on the genetic variations.1

Clinical Utility

  • To Diagnose the disease -causing variants associated with the suspected cases.
  • Differentiation between de novo(new unexplained mutations) and familial history of disorders.
  • To influence the management of the conditions/disorders in a better way including lifestyle interventions.

When is WES Recommended?

  • Molecular Diagnosis - identify the variations in the exon regions, variants of a disease or disease-causing mutations associated in suspected cases.
  • Undiagnosed Conditions - In cases where no diagnosis has been made, but clinical presentation is suggestive of a genetic condition.
  • Detect disease-causing heterozygous variants in genes associated with autosomal dominant conditions, homozygous/compound heterozygous variants in genes associated with autosomal recessive conditions.
  • Test for single-gene and multigene conditions. Ideal for targeted management of complex syndromes. - neurodevelopmental disorders, intellectual disability, global developmental delay, autism spectrum disorder.
  • To end the Diagnostic Odyssey.
  • Provide accurate recurrence risks for family members & prognosis.

MapmyGenome - Offerings

  • Extensive coverage of all genes in the human genome ~23000 genes & mitochondrial genes
  • Raw data is analyzed using a comprehensive bioinformatics pipelines
  • Pathogenic, Likely Pathogenic, VuS are reported as per the ACMG guidelines & ClinVar
  • Covers more than 98% of targeted exons, with a Sensitivity of 95.9% & Specificity of 98.7%
  • Genetic counseling - to guide through the report and discuss the availability management/treatment options in case of clinical findings
  • Primary findings are reported according to the clinical phenotype & ACMG guidelines. Incidental findings and carrier findings are reported as per ACMG and ACOG recommendations.

Test specification

                                                               
Technique Coverage Variant types TAT Sample requirements
NGS 150 - 180x SNV + CNV 3 -4 weeks CVS Sample, Amniotic Fluid, Cultured Cells - Cell Pellet in 1.5mL tube, Extracted DNA samples (1µg - 2µg), 3-4ml EDTA Blood, FFPE (Formalin-Fixed Paraffin-Embedded) Sample - Somatic cases

References

  1. Rabbani, B., Tekin, M. & Mahdieh, N. The promise of whole-exome sequencing in medical genetics. J Hum Genet 59, 5–15 (2014). https://doi.org/10.1038/jhg.2013.114